Multisensory integration (MSI), the combination of various senses to form a single integrated percept of the world, is essential to everyday life. A number of research studies have suggested that development of basic sensory processing and multisensory integration are affected in children with autism spectrum disorders (ASD). The proposed project will examine behavioral and dense-array scalp-recorded EEG measures to brief auditory and somatosensory stimuli in children with ASD as compared to typically developing (TD) children. We will test 40 11.5- 13.5 yr. old children with ASD and 20 TD children matched on age, sex, handedness and IQ. We will examine auditory / somatosensory integration through analysis of event related potentials elicited in response to auditory and somatosensory stimuli delivered alone or in combination. The task will be the detection of stimulus events in a simple reaction time (RT) paradigm. Differences between multisensory and the summed responses of identical constituent stimuli will be used as a measure of MSI. We predict that on the basis of preliminary data, compared with TD children, children with ASD will show less RT facilitation and smaller electrocortical activations related to multisensory integration. We further predict that there will be less evidence of intersensory inhibition in the ASD group. We will relate measures of MSI to ASD symptom severity and predict more impairment with increased symptom severity. We will also examine single-modality sensory activations and sensorimotor integration by examining the antecedent cortical activations prior to manual RT responses using stimulus- and response time locked averages. The uniqueness and strength of this proposal lie in its application of a well-developed neuroscientific model of multisensory integration to investigate brain bases of sensory problems in ASD. The proposed project also takes advantage of reliable recruitment support at the M.I.N.D. Institute, UC Davis. The proposed study will provide a neurophysiological model of sensory problems in autism spectrum disorders, which will help lay foundation for future treatment studies that could improve life of affected individuals.!! PUBLIC HEALTH RELEVANCE: A number of research studies have suggested that basic sensory processing and formation of cross-sensory associations are affected in children with autism. We will investigate cross-sensory integration in ASD, in particular combination of sound and touch, through examinations of behavioral reaction time data and spatial and temporal patterns of brain activity in brain regions that are involved in processing and integration of sensory information. Establishing the brain basis of sensory problems in ASD will help us lay foundation for future treatment studies, which can lead to improved life of affected individuals.!!